BONJOUR (Dissertation, 1970, ETH Zuerich) and HASHIMOTO (Yakugaki Zasshi 80, (1960), 1399-1404) describe the preparation of azo dyes on the basis of trimethylsilanilines by reaction of these silicon compounds with diazotized aromatic amines. Dyes of this type are not suitable for adhering to the substances to be dyed because of their inactive methyl groups at the silicon atom. They have consequently not resulted in industrial use of any importance.
From U.S. Pat. Nos. 3,888,891, 3,963,774 and 3,981,859 dyes have become known which contain a tris-(trimethylsiloxy-)silylalkylamino radical. These are mainly quinone-, indigo-, thioindigo-, phthalocyanine- and azo dyes. Apart from the fact that for the preparation of the tris-(trimethylsiloxy-)silylalkylamino compound expensive reactions have to be carried out and the silane is only obtained in a low yield, these dyes have only limited use in the dyeing of certain polyorganosiloxanes because their siloxy radicals are very ineffective.
Silicon-containing dyes, which already have a hydrolyzable radical capable of imparting adherence, are for instance described in U.S. Pat. Nos. 2,925,313, 2,927,839, 2,931,693, 2,934,459, 2,955,898, 2,955,899 and 2,963,338. In these cases, arylamino- or aminoarylalkylalkoxy-silanes were used as starting compounds for the production of azo dyes. These dyes adhere well to glass fibers, natural fibers, such as wool, silk and cotton, as well as to synthetic fibers. A disadvantage, however, In that case, too, the preparation of the silicon-containing amino starting materials is cumbersome and expensive, and the results are unsatisfactory.
Silicon-containing nitro dyes of the structure disclosed by the invention have not been described in the literature up to now.